Isabel Baillie is, perhaps, the English singer most associated with purity, clarity and focus. But she too had her Wagner moment, singing Act 2 of Tristan and Isolde in a broadcast. Famously, Sir Hamilton Harty heard the broadcast and informed her that he would no longer work with her if she persisted in singing Wagner. Again, it is a surprise to us that she attempted it at all, even though the producer of the broadcast was looking to prove a theory about Isolde being a role for a lyric soprano. The tenor on that broadcast was Walter Widdop. Widdop was a Wagner tenor with an international reputation but he ran this career in parallel with singing Handelian oratorio. His Messiah was probably rather heavier and slower than we would consider nowadays, but I suspect that few contemporary Siegmunds possess the sort of clear, focussed voices that would enable them to do a similar feat.

Similarly Lilian Nordica, the dramatic soprano who had expected to sing Brünnhilde in 1896 in New York when Melba took her place, was a renowned dramatic soprano, the first non-German to sing all three Brünnhildes and Isolde. In fact, it was hearing Nordica sing Elsa that caused Melba to add the role to her repertoire. But Nordica continued to programme a wide repertoire of roles ranging from Valentine (in Les Huguenots) to Violetta and even the Queen of the Night (a role she dropped towards the end of her career).

But before we get all romantic about how voice production has changed and how wonderful these old voices were, we must consider the final change that has happened to the musical world. Simply, orchestras have got louder, much louder.

During the first half of the 20th century orchestral power increased significantly; strings have replaced metal with gut and the bores of brass instruments have increased, with a commensurate increase in power. At the forefront of this revolution was Arturo Toscanini as these instrumental changes were allied to his campaigns to increase technical skill, discipline and professionalism within the orchestra.

So, in the end, we must probably decide that the past is another country, they do things differently there. We can never securely re-capture the sound that Melba made when she sang Brünnhilde at the Metropolitan Opera; too much has changed in nearly a century.

I realise that these musings are a very personal view. Undertaking generalisations is always a risky business; there are probably discs out there which could be made to contradict me. But I think that too little consideration is given to the way that singers of the past produced their voices. So, in an age when we are starting to explore Wagner on period instruments, it is worth bearing in mind that without a radical change in the way singers vocalise, these explorations will only bear limited fruit.